UPDATE ......From Tuesday 8 April 2025 we have changed the way that Single Sign-on works on this wiki. Please see here for more information:
Update
As a project administrator you can control who has access to your project (display tickets, etc.) as well restrict specified acciviti for particular team members. It is possible to grant permission to display and create tickets while not allowing to remove it.
There are two sections (see picture below) in project settings dedicated to manage project permissions and roles.